The present invention relates to a laser beam display device that uses a laser diode as a light source, and displays a gray-scale image by scanning a laser beam with the use of a deflection component, and at the same time, by modulating the laser intensity of the beam light in accordance with an input image.
Thanks to the improvement of semiconductor laser technology in recent years, a light output of high power with desired wavelength components has been available. In addition, thanks to the improvement of semiconductor components and the advancement of packaging technology and the like, the efficiency improvement of electro-photo conversion and the downsizing and price-reduction have been realized, with the result that semiconductor devices are now used for various applications. For example, a beam light with visible light wavelength components the emission amount of which is modulated by a video signal is disclosed in Japanese Unexamined Patent Application Publication No. 2006-343397, and this beam light reflected by a micro mirror, which monoaxially or biaxially vibrates with the use of MEMS (Micro Electro Mechanical System) technology, has been widely applied to an image display device that performs raster scanning on an object.
On the other hand, the drive current vs. light output power characteristic (I-L characteristic) of a laser diode (LD) used for a light source is involved with the emission region of an LED and the oscillation region of the laser diode, and it is necessary to apply a predefined threshold current to the laser diode in order for the laser diode to emit the laser light. In addition, it is known that the light output power in a laser oscillation region does not have an excellent linearity to the drive current. In addition, it is also known that this output power characteristic depends on each laser diode, and varies in accordance with the temperature and aged deterioration of the laser diode.